Question

Solve the system:
y = -2x + 9
y = 3x + 9

Answer 1

(0, 9)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Equality Properties

• Multiplication Property of Equality
• Division Property of Equality
• Addition Property of Equality
• Subtract Property of Equality

Algebra I

• Terms/Coefficients
• Coordinates (x, y)
• Solving systems of equations using substitution/elimination

Explanation:

Step 1: Define Systems

y = -2x + 9

y = 3x + 9

Step 2: Solve for x

Substitution

1. Substitute in y: 3x + 9 = -2x + 9
2. [Addition Property of Equality] Add 2x on both sides: 5x + 9 = 9
3. [Subtraction Property of Equality] Subtract 9 on both sides: 5x = 0
4. [Division Property of Equality] Divide 5 on both sides: x = 0

Step 3: Solve for y

1. Define equation: y = -2x + 9
2. Substitute in x: y = -2(0) + 9
3. Multiply: y = 0 + 9
4. Add: y = 9